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    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
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<body>
    <script>
        // 非严格模式
        function test1(a){
            arguments[0] = 34;
            console.log(a);
        }
        // 严格模式
        function test2(a){
            "use strict";
            arguments[0] = 34;
            console.log(a);
        }
        
        // function test3(a,b = 10){
        //     'use strict' //会报错
        // };

        test1(20);
        test2(20);
        // test3(5);        




    </script>
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